The bottom side probably looks great. If you change one of these filters and study the intake box, you will see how debris collects on the top, but falls off on the sides and does not collect on the bottom. And as air filters go, the used stock one in the picture is not bad or clogged up enough to cost 15 hp.

You have not ever changed your filter clearly. Leaves and bigger debree collect on top as its a function of vacuum and gravity that they get sucked and settle on top. The dirt and smaller dust etc is directed from the road with almost a straight shot into the bottom of the intake. The top is getting air from the grilles and the hood vent at high speeds, relatively cleaner air than the road grime.

hey I need a filter and been looking at various offerings from Dinan, MS, AA, etc.

Maybe a dumb question but since you can't see it why does the color matter? So no one runs open air elements anymore?

Is the Dinan setup include a different airbox of still just a drop in?

Would like to order one this week!

Will teaming this up with RPI scoops help?

Color doesn't matter. The K&N filter is red because their filter oil is red. The filter oil is probably red because red is their color.

The scoops positively do (basically, see below) nothing. It is physically impossible for them to generate a "ram air" effect with this intake design. The only possible benefit would be less heat soak due to more air flow THROUGH (i.e. from the scoops, through the box, up and out of the hood vent) the box.

Any purported dyno "gains" are from "fudging" the numbers. The quoted "gains" are within the accepted variance of the dyno. Pick and choose the right runs and voila, gains. Do enough runs and average them all, I bet you'd see zero gains.

I've never seen any objective data to suggest there was any measurable HP gain by using a K&N filter.

I have seen anectdotal evidence over ten years of owning a BMW of people gumming up their MAF sensor by over-oiling.

I have always used, and believe in, only genuine OEM filters for my cars.

YMMV of course. Just my 0.02.

__________________

Character does count. For too long we have gotten by in a society that says the only thing right is to get by and the only thing wrong is to get caught. Character is doing what's right when nobody is looking... " --J. C. Watts

I've never seen any objective data to suggest there was any measurable HP gain by using a K&N filter.

I have seen anectdotal evidence over ten years of owning a BMW of people gumming up their MAF sensor by over-oiling.

I have always used, and believe in, only genuine OEM filters for my cars.

YMMV of course. Just my 0.02.

Our car doesn't have a MAF. My 350Z did. I ran a K&N filter for 5 years. One time, I oiled the filter so much that my car left a puddle on the ground, I thought it was leaking oil! My MAF was not affected and my 350Z made great power.

I just installed a K&N filter last night. Don't notice much except it is a little louder at higher revs.

Your 2009 MY is in the category that will get the most benefits from changing the filter (by getting rid of that charcoal liner). However, 2-5hp is not something you will obviously notice from the seat of the pants. But all the small improvements combined together do eventually add up.

Your 2009 MY is in the category that will get the most benefits from changing the filter (by getting rid of that charcoal liner). However, 2-5hp is not something you will obviously notice from the seat of the pants. But all the small improvements combined together do eventually add up.

Yup, I have no doubt that it is performing better than the stock filter, but like you said, difficult to feel a 1% gain in power. I have ordered other bolt-ons (test pipes & pulleys) and can't wait to have them all come together along with a tune. Then I should definitely feel a difference!

I have a KN, its awesome, no vibrations. Sounds a bit better. The car felt slightly more responsive but then again I did have a dirty stock filter. I bought it when Advanced auto had a sale and it was 55 bucks.